Estimation techniques of a point of gaze (Point-Of-Gage; POG) have been studied long and are applied to many fields relating to dialogue with a computer, such as information input to a computer and observation of a target of attention of a person on a web browser. To achieve high-accuracy point-of-gaze estimation, accurate measurement of a center of curvature of a cornea and a center of a pupil is carried out in consideration of optical refraction in some cases.
On the other hand, in a case of applying the point-of-gaze estimation technique to an application like e.g. a game, it is required that point-of-gaze control can be easily carried out through comfortable operation rather than that always a point of gaze is accurately estimated. In other words, a technique by which a cursor can be accurately aligned on a target with a line of sight put on the target is desired.